Printed wire assemblies (PWA) are formed of electronic components soldered to a circuit board. They and other such electronic components need to be cleaned after manufacture to remove various contaminants such as solder flux, solder balls and other such soils. Failure to remove these soils can cause dielectric breakdown of the components, corrosion, poor conformal coat adhesion and poor electrical contact as well as being cosmetically unacceptable.
Traditionally, chlorofluorocarbons (CFCs) have been used to remove these soils. However, the use of CFCs has come under increased restrictions due to their propensity to destroy the ozone layer and contribute to global warming.
Other solvent based or semi-aqueous cleaners have been proposed and used. While they provide adequate cleaning, they also have come under additional scrutinty. For example, some solvents are believed to cause various health problems. Additionally, many are also believed to contribute to global warming. Lastly, the waste stream generated by these systems is difficult to dispose of, often requiring incineration.
Alkaline aqueous based cleaners are becoming the preferred cleaners. These materials contain no CFCs or solvents and therefore are relatively safety to use. Moreover, due to the large amount of water used with such systems and thereby corresponding small amounts of chemicals, the standard practice has been to use the cleaner once and dispose of the soiled cleaner in a waste treatment process.
The expense of waste treatment and of the cleaner itself as well as the restrictions on water usage that have been imposed in various portions of the United States has developed a need for a process by which the cleaner and water can recycled.
The present invention provides a system and a process for recycling alkaline aqueous cleaners which reduces the consumption of cleaner and water and which reduces the need for and cost of waste treatment.